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Linux/fs/hfs/btree.c

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  1 /*
  2  *  linux/fs/hfs/btree.c
  3  *
  4  * Copyright (C) 2001
  5  * Brad Boyer (flar@allandria.com)
  6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
  7  *
  8  * Handle opening/closing btree
  9  */
 10 
 11 #include <linux/pagemap.h>
 12 #include <linux/slab.h>
 13 #include <linux/log2.h>
 14 
 15 #include "btree.h"
 16 
 17 /* Get a reference to a B*Tree and do some initial checks */
 18 struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp keycmp)
 19 {
 20         struct hfs_btree *tree;
 21         struct hfs_btree_header_rec *head;
 22         struct address_space *mapping;
 23         struct page *page;
 24         unsigned int size;
 25 
 26         tree = kzalloc(sizeof(*tree), GFP_KERNEL);
 27         if (!tree)
 28                 return NULL;
 29 
 30         mutex_init(&tree->tree_lock);
 31         spin_lock_init(&tree->hash_lock);
 32         /* Set the correct compare function */
 33         tree->sb = sb;
 34         tree->cnid = id;
 35         tree->keycmp = keycmp;
 36 
 37         tree->inode = iget_locked(sb, id);
 38         if (!tree->inode)
 39                 goto free_tree;
 40         BUG_ON(!(tree->inode->i_state & I_NEW));
 41         {
 42         struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
 43         HFS_I(tree->inode)->flags = 0;
 44         mutex_init(&HFS_I(tree->inode)->extents_lock);
 45         switch (id) {
 46         case HFS_EXT_CNID:
 47                 hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
 48                                     mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
 49                 if (HFS_I(tree->inode)->alloc_blocks >
 50                                         HFS_I(tree->inode)->first_blocks) {
 51                         pr_err("invalid btree extent records\n");
 52                         unlock_new_inode(tree->inode);
 53                         goto free_inode;
 54                 }
 55 
 56                 tree->inode->i_mapping->a_ops = &hfs_btree_aops;
 57                 break;
 58         case HFS_CAT_CNID:
 59                 hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
 60                                     mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
 61 
 62                 if (!HFS_I(tree->inode)->first_blocks) {
 63                         pr_err("invalid btree extent records (0 size)\n");
 64                         unlock_new_inode(tree->inode);
 65                         goto free_inode;
 66                 }
 67 
 68                 tree->inode->i_mapping->a_ops = &hfs_btree_aops;
 69                 break;
 70         default:
 71                 BUG();
 72         }
 73         }
 74         unlock_new_inode(tree->inode);
 75 
 76         mapping = tree->inode->i_mapping;
 77         page = read_mapping_page(mapping, 0, NULL);
 78         if (IS_ERR(page))
 79                 goto free_inode;
 80 
 81         /* Load the header */
 82         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
 83         tree->root = be32_to_cpu(head->root);
 84         tree->leaf_count = be32_to_cpu(head->leaf_count);
 85         tree->leaf_head = be32_to_cpu(head->leaf_head);
 86         tree->leaf_tail = be32_to_cpu(head->leaf_tail);
 87         tree->node_count = be32_to_cpu(head->node_count);
 88         tree->free_nodes = be32_to_cpu(head->free_nodes);
 89         tree->attributes = be32_to_cpu(head->attributes);
 90         tree->node_size = be16_to_cpu(head->node_size);
 91         tree->max_key_len = be16_to_cpu(head->max_key_len);
 92         tree->depth = be16_to_cpu(head->depth);
 93 
 94         size = tree->node_size;
 95         if (!is_power_of_2(size))
 96                 goto fail_page;
 97         if (!tree->node_count)
 98                 goto fail_page;
 99         switch (id) {
100         case HFS_EXT_CNID:
101                 if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
102                         pr_err("invalid extent max_key_len %d\n",
103                                tree->max_key_len);
104                         goto fail_page;
105                 }
106                 break;
107         case HFS_CAT_CNID:
108                 if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
109                         pr_err("invalid catalog max_key_len %d\n",
110                                tree->max_key_len);
111                         goto fail_page;
112                 }
113                 break;
114         default:
115                 BUG();
116         }
117 
118         tree->node_size_shift = ffs(size) - 1;
119         tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
120 
121         kunmap(page);
122         page_cache_release(page);
123         return tree;
124 
125 fail_page:
126         page_cache_release(page);
127 free_inode:
128         tree->inode->i_mapping->a_ops = &hfs_aops;
129         iput(tree->inode);
130 free_tree:
131         kfree(tree);
132         return NULL;
133 }
134 
135 /* Release resources used by a btree */
136 void hfs_btree_close(struct hfs_btree *tree)
137 {
138         struct hfs_bnode *node;
139         int i;
140 
141         if (!tree)
142                 return;
143 
144         for (i = 0; i < NODE_HASH_SIZE; i++) {
145                 while ((node = tree->node_hash[i])) {
146                         tree->node_hash[i] = node->next_hash;
147                         if (atomic_read(&node->refcnt))
148                                 pr_err("node %d:%d still has %d user(s)!\n",
149                                        node->tree->cnid, node->this,
150                                        atomic_read(&node->refcnt));
151                         hfs_bnode_free(node);
152                         tree->node_hash_cnt--;
153                 }
154         }
155         iput(tree->inode);
156         kfree(tree);
157 }
158 
159 void hfs_btree_write(struct hfs_btree *tree)
160 {
161         struct hfs_btree_header_rec *head;
162         struct hfs_bnode *node;
163         struct page *page;
164 
165         node = hfs_bnode_find(tree, 0);
166         if (IS_ERR(node))
167                 /* panic? */
168                 return;
169         /* Load the header */
170         page = node->page[0];
171         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
172 
173         head->root = cpu_to_be32(tree->root);
174         head->leaf_count = cpu_to_be32(tree->leaf_count);
175         head->leaf_head = cpu_to_be32(tree->leaf_head);
176         head->leaf_tail = cpu_to_be32(tree->leaf_tail);
177         head->node_count = cpu_to_be32(tree->node_count);
178         head->free_nodes = cpu_to_be32(tree->free_nodes);
179         head->attributes = cpu_to_be32(tree->attributes);
180         head->depth = cpu_to_be16(tree->depth);
181 
182         kunmap(page);
183         set_page_dirty(page);
184         hfs_bnode_put(node);
185 }
186 
187 static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
188 {
189         struct hfs_btree *tree = prev->tree;
190         struct hfs_bnode *node;
191         struct hfs_bnode_desc desc;
192         __be32 cnid;
193 
194         node = hfs_bnode_create(tree, idx);
195         if (IS_ERR(node))
196                 return node;
197 
198         if (!tree->free_nodes)
199                 panic("FIXME!!!");
200         tree->free_nodes--;
201         prev->next = idx;
202         cnid = cpu_to_be32(idx);
203         hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
204 
205         node->type = HFS_NODE_MAP;
206         node->num_recs = 1;
207         hfs_bnode_clear(node, 0, tree->node_size);
208         desc.next = 0;
209         desc.prev = 0;
210         desc.type = HFS_NODE_MAP;
211         desc.height = 0;
212         desc.num_recs = cpu_to_be16(1);
213         desc.reserved = 0;
214         hfs_bnode_write(node, &desc, 0, sizeof(desc));
215         hfs_bnode_write_u16(node, 14, 0x8000);
216         hfs_bnode_write_u16(node, tree->node_size - 2, 14);
217         hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
218 
219         return node;
220 }
221 
222 struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
223 {
224         struct hfs_bnode *node, *next_node;
225         struct page **pagep;
226         u32 nidx, idx;
227         unsigned off;
228         u16 off16;
229         u16 len;
230         u8 *data, byte, m;
231         int i;
232 
233         while (!tree->free_nodes) {
234                 struct inode *inode = tree->inode;
235                 u32 count;
236                 int res;
237 
238                 res = hfs_extend_file(inode);
239                 if (res)
240                         return ERR_PTR(res);
241                 HFS_I(inode)->phys_size = inode->i_size =
242                                 (loff_t)HFS_I(inode)->alloc_blocks *
243                                 HFS_SB(tree->sb)->alloc_blksz;
244                 HFS_I(inode)->fs_blocks = inode->i_size >>
245                                           tree->sb->s_blocksize_bits;
246                 inode_set_bytes(inode, inode->i_size);
247                 count = inode->i_size >> tree->node_size_shift;
248                 tree->free_nodes = count - tree->node_count;
249                 tree->node_count = count;
250         }
251 
252         nidx = 0;
253         node = hfs_bnode_find(tree, nidx);
254         if (IS_ERR(node))
255                 return node;
256         len = hfs_brec_lenoff(node, 2, &off16);
257         off = off16;
258 
259         off += node->page_offset;
260         pagep = node->page + (off >> PAGE_CACHE_SHIFT);
261         data = kmap(*pagep);
262         off &= ~PAGE_CACHE_MASK;
263         idx = 0;
264 
265         for (;;) {
266                 while (len) {
267                         byte = data[off];
268                         if (byte != 0xff) {
269                                 for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
270                                         if (!(byte & m)) {
271                                                 idx += i;
272                                                 data[off] |= m;
273                                                 set_page_dirty(*pagep);
274                                                 kunmap(*pagep);
275                                                 tree->free_nodes--;
276                                                 mark_inode_dirty(tree->inode);
277                                                 hfs_bnode_put(node);
278                                                 return hfs_bnode_create(tree, idx);
279                                         }
280                                 }
281                         }
282                         if (++off >= PAGE_CACHE_SIZE) {
283                                 kunmap(*pagep);
284                                 data = kmap(*++pagep);
285                                 off = 0;
286                         }
287                         idx += 8;
288                         len--;
289                 }
290                 kunmap(*pagep);
291                 nidx = node->next;
292                 if (!nidx) {
293                         printk(KERN_DEBUG "create new bmap node...\n");
294                         next_node = hfs_bmap_new_bmap(node, idx);
295                 } else
296                         next_node = hfs_bnode_find(tree, nidx);
297                 hfs_bnode_put(node);
298                 if (IS_ERR(next_node))
299                         return next_node;
300                 node = next_node;
301 
302                 len = hfs_brec_lenoff(node, 0, &off16);
303                 off = off16;
304                 off += node->page_offset;
305                 pagep = node->page + (off >> PAGE_CACHE_SHIFT);
306                 data = kmap(*pagep);
307                 off &= ~PAGE_CACHE_MASK;
308         }
309 }
310 
311 void hfs_bmap_free(struct hfs_bnode *node)
312 {
313         struct hfs_btree *tree;
314         struct page *page;
315         u16 off, len;
316         u32 nidx;
317         u8 *data, byte, m;
318 
319         hfs_dbg(BNODE_MOD, "btree_free_node: %u\n", node->this);
320         tree = node->tree;
321         nidx = node->this;
322         node = hfs_bnode_find(tree, 0);
323         if (IS_ERR(node))
324                 return;
325         len = hfs_brec_lenoff(node, 2, &off);
326         while (nidx >= len * 8) {
327                 u32 i;
328 
329                 nidx -= len * 8;
330                 i = node->next;
331                 hfs_bnode_put(node);
332                 if (!i) {
333                         /* panic */;
334                         pr_crit("unable to free bnode %u. bmap not found!\n",
335                                 node->this);
336                         return;
337                 }
338                 node = hfs_bnode_find(tree, i);
339                 if (IS_ERR(node))
340                         return;
341                 if (node->type != HFS_NODE_MAP) {
342                         /* panic */;
343                         pr_crit("invalid bmap found! (%u,%d)\n",
344                                 node->this, node->type);
345                         hfs_bnode_put(node);
346                         return;
347                 }
348                 len = hfs_brec_lenoff(node, 0, &off);
349         }
350         off += node->page_offset + nidx / 8;
351         page = node->page[off >> PAGE_CACHE_SHIFT];
352         data = kmap(page);
353         off &= ~PAGE_CACHE_MASK;
354         m = 1 << (~nidx & 7);
355         byte = data[off];
356         if (!(byte & m)) {
357                 pr_crit("trying to free free bnode %u(%d)\n",
358                         node->this, node->type);
359                 kunmap(page);
360                 hfs_bnode_put(node);
361                 return;
362         }
363         data[off] = byte & ~m;
364         set_page_dirty(page);
365         kunmap(page);
366         hfs_bnode_put(node);
367         tree->free_nodes++;
368         mark_inode_dirty(tree->inode);
369 }
370 

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